was wondering if i could 'refresh' the dropdown list on combobox component?

the case is i'm using dynamic data/store to populate a combobox, first the combo box has 3 row, and then when i update the data to more than 3 (or vice versa) the dropdown layout doesnt seems to fit anymore, and sometime it cross the dropdown border.

on mobile screen it looks ok i think, but on ipad or larger screen, when combobox appear as popup, the problem appear.

i try several command one of it is doComponentLayout, no luck :)
and im sure a simple command or css could do the trick?